JERUSALEM - Israel's prime minister is trying to capitalize on the gruesome video of an American journalist's beheading by the Islamic State extremist group, saying Hamas is an equally vicious foe as he tries to rally international support in Israel's war in the Gaza Strip. But the comparisons between Hamas and Islamic State are being met with reservations by Israel's allies and enemies alike.

Prime Minister Benjamin Netanyahu always has prided himself on his ability to attract media attention. Netanyahu, who grew up in the U.S. and speaks fluent English, often uses catchy quips, props or visual aids in public speeches or briefings to journalists.

A day after the Islamic State group, also known as ISIS, posted the video of journalist James Foley's killing, Netanyahu debuted his latest catchphrase: "Hamas is ISIS. ISIS is Hamas." He voiced the slogan at a news conference, on Twitter and even at his weekly Cabinet meeting Sunday.

As Israel's military campaign against Hamas in Gaza nears its eighth week, Netanyahu is fighting an uphill battle for international support. While the international community generally supports Israel's right to defend itself against indiscriminate rocket fire, the world has grown increasingly uncomfortable with the scenes coming out of Gaza.

Hundreds of Israeli airstrikes, along with tank and artillery fire, have killed more than 2,100 people and caused widespread destruction. U.N. and Palestinian officials say most of the dead have been civilians, including some 500 children.

With powerful images of flattened buildings and dead children coming out of Gaza each day, Israel's argument that the civilians have been used as "human shields" by Hamas seems to be making little difference to perceptions abroad. Sixty-eight people have been killed on the Israeli side, all but four of them soldiers.

"There is complete agreement, almost a consensus, that (the Islamic State group) is a monstrous organization. But there is no international agreement that Hamas is a monstrous organization," veteran Israeli television commentator Moti Kirschenbaum said.

Perhaps with this distinction in mind, Netanyahu has tried to frame the military operation in Gaza not as a local conflict, but as part of a broader global fight against a unified Islamist threat.

"Many countries in the region and the West are beginning to understand that this is one front," Netanyahu said Sunday. "They are branches of the same poisoned tree."

He said both groups had carried out extra-judicial killings, a nod to Hamas' public shooting Friday of suspected spies for Israel.

But his pairing of Hamas and the Islamic State group has hit bumps.

When asked about Netanyahu's comparison last week, U.S. State Department spokeswoman Marie Harf said the U.S. considers both groups terrorist organizations, but said: "I think by definition they are two different groups. They have different leadership. And I'm not going to compare them in that way."

Netanyahu's office posted a graphic on Twitter of an image from the Islamic State video of journalist Foley kneeling next to his killer, paring it with a 2012 photo of a Hamas motorcyclist dragging an accused spy's corpse. But it quickly deleted the tweet amid world criticism over images of the video being shared on social media.

In subsequent tweets, Netanyahu's office replaced the image with a picture of the black Islamic State group's flag.

Israeli journalist Amir Tibon, writing on the news website Walla, called the comparison hypocritical because Israel has held negotiations with Hamas over a long-term cease-fire, while the U.S. refuses to negotiate with the Islamic State group - and because Hamas has not beheaded American journalists in Gaza.

"Journalists who strayed from Hamas's strict line and reported on rocket fire at Israel, were threatened, and in extreme cases, expelled from Gaza, but none of them ended their lives like James Foley," Tibon said.

Hamas itself condemned Netanyahu's comparison, saying its battle is against Israel, not against the entire West.

Hamas official Izzat Risheq said James Foley was "executed in a brutal matter."

Hamas is a "national liberation movement" whose forces are "freedom fighters who are seeking the liberation of the Palestinian people and their civil rights," Risheq said.

Since Hamas overran the territory in 2007, it has cautiously attempted to enforce its deeply conservative version of Islam and has at times placed some restrictions on women's behavior. But it has refrained from passing sweeping Islamic legislation and rescinded certain orders, apparently fearing a public backlash.

Hamas also claims it protects religious minorities. But under its rule, Christians have felt embattled and their numbers have dwindled through emigration.

Yoram Schweitzer, a researcher at Israel's Institute for National Security Studies, said unlike the Islamic State group, Hamas believes in postponing full implementation of Islamic religious law to a later stage and has taken part in democratic elections, he said.

"In this sense Hamas is more pragmatic," Schweitzer said. But he added that "Hamas, whether ISIS or not ISIS, is a very brutal organization."